Numerous different filter systems have been employed to filter or clarify water or wastewater. Previously developed filter systems include upflow filters, downflow filters, bi-flow filters as well as filter systems including a combination of two or more of the aforementioned filters. Modular filter systems have also been used to filter water and/or wastewater. Modular filter systems have a plurality of filter compartments or cells rather than a single large filter bed for a given unit. Modular filter systems were primarily developed to reduce the size and complexity of the backwash or cleaning structure of single, large filter beds as well as obviate the need for a total system shutdown during the backwash or cleaning procedure.
Various means have been employed to direct influent to the filter to remove the desired amount of impurities from the influent. These means include piping or similar conduits that direct influent upwardly or downwardly through a filter bed. Further, troughs have been used to direct influent downwardly through one or more filter beds. It is important to control the flow of influent to the filter bed in order to optimize the efficiency of the filter. For example, gravel layers have been used in upflow filters to uniformly distribute influent through a filter bed. Concrete, arcuate weir blocks have been used to control the flow of influent from a feed trough to one or more denitrification filter compartments as is disclosed in U.S. Pat. No. 5,496,472. These weir blocks are placed on the uppermost horizontal surface of the feed trough. The juncture between the weir blocks and the uppermost horizontal surface of the feed trough must be adequately sealed. Further, the weir blocks must be must be adequately secured to the feed trough. These concrete weir blocks are not a cost effective means to control the flow of influent from the feed trough to the corresponding filter beds. Further, the weir blocks are time consuming to install. The elimi-Nite system marketed by F. B. Leopold replaces the concrete, arcuate weir blocks with a curved stainless steel weir. This type of weir suffers from similar problems as those encountered by the concrete, arcuate weir block.